Principal Investigator: Fisher. Aron B. PROJECT #6: LYSOSOMAL PHOSPHOLIPASE A2 IN LUNG DPPC METABOLISM Name eraCommons Role on Project Affiliation Aron B. Fisher, M.D. abfifem Responsible Invest. Univ. Penn Sheldon I. Feinstein, Ph.D. feinsteins Co-Investigator Univ. Penn Yefim Manevich, Ph.D. Co-Investigator Univ. Penn Brian Bahnson, Ph.D. Participating Univ. Del Investigator Tomo Oe, Ph.D. Participating Univ. Penn Investigator Position Professor and Director Sr. Research Invest. Sr. Research Invest. Associate Professor Res. Asst. Professor ABSTRACT This project will evaluate the properties and physiological role of a novel phospholipase A2 (aiPLA2) that is one of the enzymatic activities of the protein called peroxiredoxin 6. We have isolated the protein from rat and bovine lungs, have identified the full length cDNA for the human, rat, mouse and bovine enzyme, have generated recombinant protein, and have developed a panel of antibodies that are effective for western blotting, immunoprecipitation and immunocytochemistry. aiPLA2 is Ca++-independent, shows maximal activity at pH 4, and represents a lysosomal-type PLA2. During the present period of grant support, we have shown that aiPLA2: 1) plays a major role in degradation of internalized alveolar DPPC; 2) provides substrate for the reacylation pathway of DPPC synthesis; 3) activity is regulated through protein-protein interactions with SP-A; 4) is localized in lung to lamellar bodies and lysosomes; 5) is activated by phosphorylation; and 6) its expression is developmental^ regulated and hormonally responsive. Specific Aim 1 will study models of under- and over-expression of aiPLA2 (knockout and transgenic mice) in order to evaluate the physiologic role of the enzyme in DPPC degradation and synthesis using isolated cells, the isolated perfused lung, and in vivo studies. Time-related (aging) changes in lung phospholipid content will be determined. Specific Aim 2 will evaluate the structure-function relationships for aiPLA2 activity utilizing